Three-axis inspection probe

ABSTRACT

An inspection probe for use in conjunction with numerically controlled machine tools is disclosed which measures deviations, at specified inspection points, from predetermined numerical dimensions along x, y or z axes in accordance with a predetermined taped program. The probe incorporates mechanical means for inhibiting x and y axis deflections while making z axis measurements, and conversely. The output may be continuously recorded by means of a pneumatic or an electrical strip chart recorder.

United States Patent 2,225,717 12/1940 Shaw 1 H1959 Steinhart 33/ 1 69C2/ 1964 Larsen 90/ 62 7/1964 Schlapp et al. 90/62 5/1966 Hilton et a1.33/172(E) FOREIGN PATENTS l/ 1964 Canada 33/23K Primary Examiner-HarryN. Haroian Attorneys-George C. Sullivan and Ralph M. Flygare ABSTRACT:An inspection probe for use in conjunction withnumerically controlledmachine tools is disclosed which measures deviations, at specifiedinspection points, from predetermined numerical dimerisions along x, yor z axes in accordance with a predetermined taped program. The probeincorporates mechanical means deflections while making z axismeasurements, and conversely. The output may be continuously recorded bymeans of a pneumatic or an electrical strip chart recorder.

for inhibiting x and y axis PATENTED mzsis n I 3.571.934

SHEET 3 0F 4 INVENTOR. ERNEST J. BUCK, SR.

. BY 7g y g Aqen s The increasing use of numerically controlled machinesfor the fabrication of machine parts has outdistanced the ability toinspect the machine parts using conventional surface plate methods.Quality assurance requires that the parts be inspected in all planes andlarge parts must be inspected by deep throated micrometers, dialindicators and other devices having special extensions which oftenrequire more than one person to complete the measurement. Such methodsof inspection not only result in a great disparity between the timerequired to manufacture the part and the time required for inspectingit, but also do not provide a permanent record of the points inspected.Techniques have been suggested heretofore to accomplish the desiredinspections by automatic means. One such technique is disclosed in U.S.Pat. No. 3,250,012 entitled Inspection Device and Method of commonassignee with the present application. While the inspection probedescribed in the mentioned patent as been found to be a significantadvance in the state-of-the-art, it has certain limitations which areovercome by the present invention. Specifically, the prior device iscapable of making dimensional measurements at numerical locationsdefined by x and y coordinates, but requires special procedures to alsomake measurements along the z axis coordinate.

SUMMARY OF THE INVENTION The present invention comprises an inspectionprobe for use in a numerically-controlled machine which provides asignal output which may be interpreted as having been obtained byapproaching the inspection point from either the x, y or z axis. Theinvention overcomes the above-mentioned limitations of prior devicessince it provides a H correspondence between measurements in all axesand includes novel means for mechanically locking out x and y axisdeflections whenever z axis measurements are being made. Conversely, theprobe is inhibited from deflecting in the x and y directions during thez-axis mode. The mode of operation is determined by the direction ofapproach of the probe to the workpiece at the time of contact. Switchingor scale shifting is avoided since the output for a given deflection isequal in all measuring modes. Furthermore, the ability to lockout the xand y modes, during 1 axis measurement, permits reliable measurements tobe made without the necessity of having a dwell period to permitmeasurement.

The apparatus of the invention greatly reduces the time required toperform three-axisinspections. Other advantages of the present inventionare its improved linearity, accuracy, and flexibility. The uniformity ofscale in all axes obviates limit switches or multiple recording channelsas IS required in certain prior inspection probe devices.

It is therefore an object of the invention to provide a novel andimproved three-axis probe device for the inspection of manufacturedparts in a numerically controlled machine.

Another object of the invention is to provide a novel and improvedmethod for the automatic inspection of manufactured parts.

Yet another object of the invention is to provide a novel and improvedinspection probe which may be mounted at the spindle of a numericallycontrolled machine which has been programmed with an inspection tape, tomake independent measurements of a part along x, y and z axes andautomatically indicate or record the measured dimensions.

Still another object of the inventionis to provide a novel and improvedmethod and apparatus for rapid inspection of manufactured parts on anumerically controlled machine wherein a threeaxis inspection probe isautomatically positioned with respect to a series of predeterminedinspection points and which transmits signals to an indicating recorderto provide a quantitative record of the deviations from predeterminednumerical dimensions at the inspection points.

It is yet another object of the invention to provide a novel andimproved three-axis inspection probe for numerically controlledmachines, having a novel lockout mechanism for precluding x and ydeflections of theprobe during the z axis measurement mode.

Another object of the invention is to provide novel and improvedinspection apparatus having greater flexibility than similar devicesemployed heretofore to accomplish generally similar purposes.

These and other objects of the invention will be better understood bymaking reference to the following description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view showing.in somewhat simplifled form, the general arrangement of a numericallycontrolled machine system incorporating the inspection device of theinvention.

FIG. 2 is a cross-sectional elevation view of a preferred embodiment ofan inspection probe constructed in accordance with the invention.

FIG. 3 is a schematic view of the apparatus of FIG. 2 show ing theapparatus in the z-axis operating mode.

FIG. 4 is a view similar to FIG. 3 showing the apparatus in the x-y axisoperating mode. 4

FIG. 5 is a detailed view of the upper end of the stylus shaftillustrating the geometry of its exterior surface.

FIG. 6 illustrates an alternative embodiment of the transdueer portionof apparatus of the type shown in FIG. 2, wherein an electrical pickoffis employed in lieu of a pneumatic sensor.

FIG. 7 is a block diagram schematically illustrating the variouscomponents of an overall inspection system incorporating the novel probeof the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I there isshown a numerically controlled bridgemill of a type suited for use withthe present invention. The machine is provided with a table I which isrectilinearly movable along orthogonal x and y coordinate axes, 2 and 3respectively. The machine is further provided with a movable spindle 4which is adapted to be rectilinearly moved along the z coordinate axis 5in accordance with a predetermined tapecontrolled program. Machining ofthe part 7 to be fabricated is accomplished with a rotating cutting tool(not shown) which is carried in the spindle 4 as will be readilyunderstood by those versed in the art. Upon completion of the machiningof part 7 the cutter is replaced with the probe device 6 of the presentinvention and, in a manner to be described hereinafter, measures themachine part 7 at a plurality of predetermined inspection points toverify its dimensions. Of course, the spindle 4 is not caused to rotateduring the inspection mode of operation. Dimensions sensed by the probe6 are transmitted in the form of an electric or pneumatic signal to arecorder 8 where they may be recorded. Also, optional gauges I1 and 12provide the operator with a visual indication of any deviation from thenominal dimension. The machine is pro vided with suitable drivemechanisms for relatively moving the part 7 and the spindle 4 and theprobe 6 along three orthogonal axes 2, 3 and 5 in accordance with apredetermined program obtained from the tape reader 9. Reference may bemade to the previously-mentioned U.S. Pat. No. 3,250,0l2 for additionaldetails of the numerically controlled machine and its tape reader. The xand y axis measurements are made independently of z axis conditions andconversely, z axis measurements are made independently of x and y axisconditions. The axis of measurement is selected automatically by thedirection of approach to the part 7, thus eliminating special switchingon the part of the operator or the machine. While locked in the z axis,a plane may be continuously traversed and measured if desired, asopposed to discrete point measuring. Also, a machined wall may betraversed vertically while the probe is locked in the x and y axes toprovide a continuous output record.

As will be seen from the foregoing description, the same machine may beused to make the part and to inspect the part, thus obviating the use ofa separate inspection machine of the types used in the prior art. 7

Referring to FIG. 2, the probe device 6 comprises a hollow cylindricalhousing 13 the upper end of which is secured to a conical shank 14having a standard taper adapted to engage the collet of the machine toolspindle 4 (shown in FIG. 1). While the arbor or shank 14 shown is of aconical configuration, other shapes adapted to engage the spindle 4 maybe substituted, in a well-known manner.

The upper end of housing 13 is provided with a circular mounting flangel5. Bolts or other suitable fastening means, one of which is indicatedat 16, are used to secure the housing 13 to the flange 15 and to shank14 via adapter plate 17. A stylus shaft 18 having a central sphericalbearing 19 is movably supported by means of fixed and movable bearingseats, 21 and 22 respectively, which are in turn contained within thehousing 13.

The lower end of the shaft 18 is provided with a detachable probecontact 39 which is adapted to contact the part to be inspected. Thethreaded fastener portion 40 and the mating tapped hole in the lower endof the shaft 18, permit the probe contact 39 to be readily removed orreplaced. While the configuration and dimensions of the contact 39 andthe length of the shaft 18 are dictated by the configuration and size ofthe part 7 to be inspected, in a typical construction they may bedimensioned to have a 1:] correspondence when reading horizontaldimensions as against vertical dimensions. In a preferred embodiment,the contact 39 has a hemispherical shape, thus providing a heightidentical to its radius and proportioned to the length of the shaft 18,such that the dimensions of the probe can be programmed into the tape atuniform increments for horizontal and vertical deflection. It should beunderstood that the geometry of the contact element may be other thanhemispherical, as dictated by specific applications. Theinterchangeability of the probe contact 39 permits the adaption of thedevice to various inspection applications. For example, the contactportion may be modified to permit inspection of narrow slots or otherpart configurations which would not be compatible with the hemisphericalcontact shown in the embodiment of FIG. 2.

Fixed bearing seat 21 is secured to the housing 13 by means of setscrews 43 whereas the movable bearing seat 22 is slidably supportedtherein. Movable seat spring 23 is partially compressed between thecylindrical spring retainer 25 and the upper end of the movable bearingseat 22. The spring retainer 25 is secured to the interior wall of thehousing 13. As can be seen, the spring retainer 25 has a centralaperture which provides clearance for the upper portion of the stylusshaft 18 to pas through. Seats 21 and 22 have complementary sphericalshapes confronting the spherical bearing 19, thus permitting shaft 18 topivot about point 24. The stylus shaft 18 may also be displaced in thedirection of arrow 26 by displacing the movable seat 22 upwardly, thusfurther compressing the spring 23.

The upper end of the stylus shaft 18 has a generally rounded contour,the detailed geometry of which will be described more fully hereinafterin connection with the description of FIG. 5. The upper, generallyrounded end of shaft 18 is adapted to engage the translation cone 27which is slidably mounted within the housing 13. A cone support spring28 has its upper end restrained by retainer 29, and the lower end of thecone support spring 28 is urged into engagement with the upper planarface of the translation cone 27. A pin 31 extending through the wall ofthe housing 13 and into the retainer 29 secures the retainer 29 againstmovement. As can be seen, the cone 27 is provided with an axial hole 32therethrough. The angle of the conical undersurface of translation cone27 is 90. A plunger 33 having a hemispherical cam surface 34 engages theupper end of the translation cone 27. The plunger 33 is axiallydisplaceable in the direction of arrow 26 to prove an output from theassociated transducer 35.

The movable seat spring 23 asserts sufficient pressure on the movableseat 22 to maintain the spherical bearing 19 firmly seated. Also, thecone support spring 28 has just sulficient force to maintain thetranslation cone 27 against the upper end of the stylus shaft 18.

In a typical construction the transducer 35 may comprise an air valvewhich communicates with the tube fitting 36 and thence to an externalpneumatic recorder via the flexible tube 37. An aperture is provided inthe sidewall of the housing 13 to accommodate fitting 36. As can beseen, the interconnection between the tube fitting 36 and the transducer35 is provided with a bend to facilitate the external connection.Modulation of the airflow in tube 37 will be recorded on the externalrecorder.

After a part (e.g., part 7) has been machined by the numericallycontrolled machine, the cutting tool is removed and the inspection probedevice of the invention is installed in its place. An inspection tape issubstituted for the cutting control tape, thus permitting the samenumerically controlled machine to be used to inspect the part. The probeis initially indexed with respect to a reference location and therecorder is set to zero. Thereafter, the probe, under the control of thetaped program, moves sequentially to a given number of inspection pointswhere it is brought into contact with the surface to be measured. Theprobe may approach the surface to be measured either horizontally orvertically, as desired. Dcpending upon the direction of approach to theinspection point, the probe will operate in one or the other of twooperat' ing modes.

Referring to FIG. 3, there is shown a first operating mode of theapparatus in which the stylus shaft 18 is vertically displaced along thez-axis 41. The mode lockout ring 38, which is secured to the stylusshaft 18, has an upper curved face of complimentary symmetry withrespect to the lower curved face of the housing 13. When the styluscontact 39 is displaced arcuately, the small clearance between theconfronting curved faces of the housing 13 and mode lockout ring 38,typically of the order of 0.001 inch, will permit the lockout ring 38 toclear the housing 13 as shown in FIG. 3. However, when the shaft 18 isdisplaced along the z-axis 4!, commencing from a free or unlockedcondition, the mode lockout ring 38 will move into the housing 13 andthereafter prevent arcuate movement about point 24 until the shaft 18 isrestored to its fully extended (unlocked) position. Movement of thestylus shaft 18 along the z-axis 41 will cause the spherical bearing 19to displace the movable bearing seat 22 in the direction of the arrow 26and apply a compressive force to spring 23.

As the contact 39 clears the elevated contour of part 42 which resultedin the z-axis displacement. the spring 23 will urge the movable bearingseat 22 downwardly and apply a restoring force to the stylus shaft 18via the bearing seat 22.

Once the measurement has been made, the probe is programmed to move awayfrom the part causing the stylus to be restored to its normal or resetposition.

A flexible rubber boot 42 encloses the lower end of housing 13 and modelockout ring 38. The upper end of the boot 42 is secured to the housing13 and the lower end is secured to shaft 18. This arrangement preventsforeign matter from entering the device and interfering with theclose-tolerance parts.

The second operating mode is illustrated in FIG. 4 wherein the contact39 has laterally approached the part 44 in the direction of arrow 45;this corresponds to movement in the horizontal plane towards aninspection point defined by x and y coordinates. As the contact 39 isdeflected by its engagement with the surface of part 44, while the probeis moving in the direction of arrow 45, shaft 18 will be caused to pivotabout point 24. The upper end of shaft 18 will move through an arcuatepath thereby causing cone 27 to be translated upwardly in the directionof arrow 46. Shaft l8 does not move upwardly when it is arcuatelydisplaced. Also, the mode lockout ring 38 moves to a position where itextends beyond the lower peripheral edge of housing 13. This preventsshaft 18 from being upwardly displaced in the direction of arrow 46since any tendency of the ring 38 to move upwardly will result in itsengagement with the housing 13 and thereby prevent further displacementin the vertical direction. Once the shaft 18 has been restored to itsinitial unlocked position, the mode lockout ring 38 will clear thehousing 13 and the probe may be programmed to make either another x-yaxis measurement or move to a z-axis measurement.

Summarizing x or y axis displacement results in arcuate motion of thespherical bearing 19 about point 24 which will cause the upper end ofthe stylus 18 to apply an upwardly directed force to the translationcone 27. This action will, in turn, upwardly displace the plunger 33 andproduce an output signal from transducer 35.

A z-axis displacement of the shaft 18 will be translated directlythrough the cone 27 along its central axis to the transducer plunger 33.Thus, the transducer plunger 33 will always be displaced in response toa rectilinear motion of the cone 27 even though the driving force to thecone 27 may result from either a direct axial translation or a vectorcomponent derived from the arcuate motion of the shaft 18. The objectiveis to make the shaft lengths on either side of pivot point 24 and thecone angles 47 and 51 such that a given displacement in the z axis willdisplace the translation cone 27 by the same amount as would the givendisplacement in the x or y axis. The manner in which the output of thetransducer is recorded will be described in detail in a subsequent ofthis specification.

In order to provide a highly linear displacement of the cone 27 isresponse to arcuate motion of the stylus shaft 18, a particulargeometric configuration of the upper end of the shaft is employed. Thiscan best be seen in FIG. 5 which is a detailed view showing an elevationcross section of the shaft end. If the upper end of the shaft 18 were tohave a spherical surface, the pivoting action of the stylus and theresulting rotation of the spherical surface against the 90 interiorangle 51 of the translation cone 27 would induce a nonlinear error intothe vertical motion of the translation cone 27. Therefore the upper endof the stylus shaft 18 is modified to have a contact surface which morenearly approximates a cone than a sphere. As can be seen, the shaft 18is provided with a curved semiconical surface 47 generated by a radius48 originating at point 49. The surface generated thereby compensatesfor the inherent nonlinearity of the vector component of the arcuatemotion of shaft 18 and results in a 1:1 correspondence between thedisplacement of the contact 39 in either the x or y axis and therectilinear displacement of the transducer plunger 33. In a practicalconstruction this has been found to reduce nonlinear errors to less than0.00065 inch in the 0.l28 inch maximum arcuate travel of the probe.

FIG. 6 illustrates an alternate embodiment of the apparatus in which anelectrical transducer 55 is employed in lieu of the pneumatic transducer35 shown in FIG. 3 and 4. As will be understood by those versed in theart, a variety of electrical pickup devices may be employed; however,alinear variable differential transformer (LVDT) has been found to be asuita ble transducer for this purpose since it produces an electricaloutput which is proportional to the linear displacement of a movablecore. The LVDT comprises a split-coil solenoid (sections 57 and 58) andan interposed excitation coil 59 which is energised with an AC carrierobtained from a fixed frequency oscillator 56. The output ofseries-connected coil sections 57 and 58 comprises an AC signal, theamplitude of which is a function of the position of a movable magneticcore 61. Coil sections 57 and 58 are wound in opposition and areconnected in series; the signal induced therein 'by displacement of core61 is supplied to a demodulator-filter 62. A DC analogue output isobtained from the demodulator-filter 62 and is amplified via amplifier63, and supplied to an electrical indicator, or recorder via terminal64.

Shaft 65 corresponds in function to shaft 33 in FIGS. 24 and it has itsupper end connected to the displaceable core 61 in the LVDT. In thenormal position of the probe, the core 61 will be centered between theoutput coils 5758 and no output will appear at the output terminal 64.Either an upward or downward displacement, as indicated by the arrow 66,will couple the carrier from the excitation coil 59 into the outputcoils 5758 and provide a resultant output at the output terminal 64,proportional to the amplitude of the mechanical displacement 66.

There is shown in FIG. 7, a block diagram of the system comprising thethree-axis probe 67, the sensor or transducer 68, the signal amplifier69, and the strip chart recorder 70. As has been stated previously, thesensor and record system may comprise either electrical or pneumaticsystems and the invention is intended to encompass both species.

The numerical data derived from the tape reader 71 is provided via line73 to the servo mechanisms which translate the probe carrying spindle ofthe numerically controlled machine 72. In response to commands from thetape reader 7], the spindle and probe 67 are moved from a referencepoint to a predetermined inspection point. The probe contact 67 will engage the part to be inspected at the given inspection point. En gagementof the probe contact will result in a displacement of the stylus shaftand a correspondingoutput will be sent via line 74, amplifier 69 andline 75 to the indicator-recorder 76.

The recorder 76 is provided with a normally-closed limit switch 78 whichopens in response to any input corresponding to a displacement in excessof 0.135 inch from the centerline of the probe. Since the drive controlof the numerically controlled machine is in, series with the limitswitch in the recorder 76, via line 77, the probe is prevented frombeing displaced in excess of 0.135 inch. The arrangement provides afail-safe feature which will prevent either the part or the probe frombeing damaged by excessive relative travel therebetween.

Prior to the time that the probe engages the part to be inspected, therecorder will read off scale in the negative direction. The transducer35 or 55 ,is adjusted so that the probe contact 39 must be displaced bya given amount before an output signal is obtained. This fixeddisplacement, referred to as the offset" is typically 0.060 inch. The0.060 inch offset requires that the probe actually engage the part to beinspected and thereafter be displaced by the amount of the offset beforea zero output signal is obtained. That is, the initial deflection of thecontact 39 will measure minus. Furthur deflection will cause therecording pen to pass zero and read plus. This scheme permits detectionof undersized pans as well as oversized parts. If the part has exactlythe desired dimensions, the output zero signal will be obtained when theprobe has been displaced by its engagement with the part by exactly0.060 inch. If the part is oversize, the output signal will be obtainedwith less than a 0.060 displacement of the probe, thus causing an outputsignal to be recorded on the negative sideof the recorders zeroreference line. Conversely, if the part is undersized, the probe must bedisplaced more than 0.060 of an inch before a zero output signal isobtained. This will cause the output to be recorded on the negative sideof the zero reference line. This arrangement permits both positive annegative tolerance measurements to be made, through an may be removedfrom the machine 7 2.

In the foregoing description it will be seen that the present inventionprovides a convenient means for inspecting machine parts utilizing, inpart, the same apparatus employed in the manufacture of the part. Thecutting tool is merely replaced with the inspection probe and the tapereader is provided with an inspection tape in lieu of the tape used inthe cutting tool. In a practical construction, measurements may be madeto an accuracy of 0.001 inch and a repeatability of 10.0005 inch.

As will be appreciated by those skilled in the art, variousmodifications, omissions, and additions may be made to the presentinvention without departing from the intended scope thereof.Accordingly, it is to be understood that the invention shall be limitedonly by the following claims.

lclaim:

1. An inspection device adapted to be selectively positioned along threeorthogonal axes relative to a workpiece for verifying the dimensionsthereof, comprising:

a hollow housing;

a stylus shaft having a first terminus extending into said hollowhousing and having a second exposed terminus for contacting saidworkpiece;

means for mounting said shaft for limited movement in three degrees ofangular freedom and one degree of rectilinear freedom;

a bearing seat fixed with respect to said housing for supporting saidmounting means;

transducer means biased into engagement with said first terminus of saidshaft and responsive to displacement thereof to generate an outputsignal; and

a lockout ring encircling said shaft and secured thereto at a locationintermediate said second exposed terminus and said mounting meanssufficient to allow clearance between said ring and said housing duringangular movement of said shaft, said ring having an exterior diametersufiiciently smaller than the interior diameter of said housing topermit said lockout ring to enter the interior of said housing inresponse to rectilinear movement along the major axis of said shaft.

2. An inspection device as defined in claim 1 including means formounting said housing in a receiving collet.

3. An inspection device as defined in claim 1 including spring means fornormally urging said stylus shaft into a position intermediate of thelimits imposed on the angular movement of said shaft.

4. An inspection device as defined in claim 1 wherein said transducermeans includes a valve operatively responsive to displacement of saidcam surface to produce a pneumatic output signal.

5. An inspection device as defined'in claim 1 wherein said transducermeans includes an electrical pickup operatively responsive todisplacement of said cam surface to produce an electrical output signal.

6. A numerically controlled machine having a collet and in combinationwith an inspection device as defined in claim 1 comprising:

a table for supporting the workpiece to be inspected;

means for imparting relative movement between the table and the collet,the inspection device being mounted in the machine collet with theexposed terminus of the stylus shaft being engageable with the workpieceon the table;

a programmed inspection tape means being coupled with the movementimparting means for controlling the relative movement between the tableand the workpiece along a predetermined path; and

a recorder coupled to the transducer means of the inspection device forindicating dimensions of the workpiece upon engagement of the workpieceand the inspection device.

7. The invention defined in claim 6 including a limit switch operativelyresponsive to said output signal to inactivate said movement impartingmeans in the event that the imposed limits of movement of said shaft areexceeded.

8. An inspection device adapted to be selectively positioned along threeorthogonal axes relative to a workpiece for verifying the dimensionsthereof, comprising:

an elongated hollow housing;

a stylus shaft having a first convex terminus, the apex of which has agenerally conical shape, extending into one end of said hollow housingand having a second exposed terminus for contacting said workpiece;

a spherical bearing fixedly secured to said shaft intermediate the endsthereof whereby said shaft is supported for movement in 3 of angularfreedom;

a stationary bearing seat fixed with respect to said housing and havinga complementary spherical surface engaging that portion of saidspherical bearing which is adjacent said second terminus; a movablebearing seat slidably mounted within said housing and having acomplementary spherical surface engaging that portion of said sphericalhearing which is ad jacent said first terminus of said shaft therebypermitting both said movable bearing seat and said stylus shaft to berectilinearly translated along the major axis of said housing in adirection to and away from said stationary bearing seat;

rectilinearly displaceablc translation element slidably mounted withinsaid housing and having a concave cam surface biased directly againstsaid first conical shape terminus of said shaft, said cam surface havinga generally complementary concave contour with respect to said conicalshape terminus, whereby angular movement in 2 of freedom and rectilinearmovement in l of freedom of said shaft will rectilinearly displace saidtranslation element along the major axis of said housing;

means connected to said shaft for mechanically inhibiting movementthereof in said 2 of angular freedom whenever said shaft isrectilinearly translated along said major axis in a direction away fromsaid stationary bearing seat; and

transducer means operatively connected to said translation element andresponsive to displacement thereof to generate an output signal.

9. An inspection device as defined in claim 8 including:

a spring retainer within said housing and secured thereto between saidmovable bearing seat and said translation element; and

a helical spring having a first end engaging said spring retainer andhaving a second end urged into engagement with said movable bearingseat.

10. An inspection device adapted to be selectively positioned alongthree orthogonal axes relative to a workpiece for verifying thedimensions thereof. comprising:

an elongated hollow housing;

a stylus shaft having a first terminus extending into one end of saidhollow housing and having a second exposed terminus for contacting saidworkpiece;

bearing means located on said shaft intermediate the ends thereof bymeans of which said shaft may be supported for movement in 3 of angularfreedom;

a stationary bearing seat fixed with respect to said housing andengaging that portion of said bearing means which is adjacent saidsecond terminus;

a movable bearing seat slidably mounted within said housing and engagingthat portion of said bearing means which is adjacent said first terminusof said shaft thereby permitting both said movable bearing seat and saidstylus shaft to be rectilinearly translated along the major axis of saidhousing in a direction to and away from said stationary bearing seat;

a translation element slidably mounted within said housing and having acam surface biased against said first terminus of said shaft wherebyangular movement in 2 of freedom and rectilinear movement in l offreedom of said shaft will displace said translation element along themajor axis of said housing;

a lockout ring encircling said shaft and secured thereto at a locationintermediate said second exposed terminus and said bearing meanssufficient to allow clearance between said ring and said housing upondisplacement of said shaft about the axis of said bearing means, saidring having an exterior diameter sufficiently smaller than the interiordiameter of said housing to permit said lockout ring to enter theinterior of said housing in response to displacement along the majoraxis r f said shaft; and

transducer means operatively connected to said translation element andresponsive to displacement thereof to generate an output signal.

'ment into direct engagement 11. The inspective device defined in claim8 wherein said transducer means comprises a valve operatively responsiveto displacement of said translation element to produce a pneumaticoutput signal.

12. An inspection device as defined'in claim 8 wherein said transducermeans comprises an electrical pickup operatively responsive todisplacement of said translation element to producean electrical outputsignal.

13. An inspection device as defined: in claim 8 including spring meanswithin said housing for urging said movable bearing seat into engagementwith *said spherical bearing 14. An inspection device as defined inclaim 8 including a helical spring normally partially compressed intoengagement with said translation element so as to urge said translationelewith said first terminus of said shaft.

15. A numerically controlled machine having a collet and in combinationwith an inspection device as defined in claim 8 comprising: v 1

a table for supporting the workpiece to be inspected;

means for imparting relative movement between the table and the collet,the inspection device being mounted in the machine collet with theexposed gterminus of the stylus shaft being engageable with theworkpiece on the table;

a programmed inspection tape means being coupled with the movementimparting means for controlling the relative movement between the tableand the workpiece along a predetennined path; and

a recorder coupled to the transducer means for indicating dimensions ofthe workpiece upon engagement of the workpiece and the inspectiondevice.

1. An inspection device adapted to be selectively positioned along threeorthogonal axes relative to a workpiece for verifying the dimensionsthereof, comprising: a hollow housing; a stylus shaft having a firstterminus extending into said hollow housing and having a second exposedterminus for contacting said workpiece; means for mounting said shaftfor limited movement in three degrees of angular freedom and one degreeof rectilinear freedom; a bearing seat fixed with respect to saidhousing for supporting said mounting means; transducer means biased intoengagement with said first terminus of said shaft and responsive todisplacement thereof to generate an output signal; and a lockout ringencircling said shaft and secured thereto at a location intermediatesaid second exposed terminus and said mounting means sufficient to allowclearance between said ring and said housing during angular movement ofsaid shaft, said ring having an exterior diameter sufficieNtly smallerthan the interior diameter of said housing to permit said lockout ringto enter the interior of said housing in response to rectilinearmovement along the major axis of said shaft.
 2. An inspection device asdefined in claim 1 including means for mounting said housing in areceiving collet.
 3. An inspection device as defined in claim 1including spring means for normally urging said stylus shaft into aposition intermediate of the limits imposed on the angular movement ofsaid shaft.
 4. An inspection device as defined in claim 1 wherein saidtransducer means includes a valve operatively responsive to displacementof said cam surface to produce a pneumatic output signal.
 5. Aninspection device as defined in claim 1 wherein said transducer meansincludes an electrical pickup operatively responsive to displacement ofsaid cam surface to produce an electrical output signal.
 6. Anumerically controlled machine having a collet and in combination withan inspection device as defined in claim 1 comprising: a table forsupporting the workpiece to be inspected; means for imparting relativemovement between the table and the collet, the inspection device beingmounted in the machine collet with the exposed terminus of the stylusshaft being engageable with the workpiece on the table; a programmedinspection tape means being coupled with the movement imparting meansfor controlling the relative movement between the table and theworkpiece along a predetermined path; and a recorder coupled to thetransducer means of the inspection device for indicating dimensions ofthe workpiece upon engagement of the workpiece and the inspectiondevice.
 7. The invention defined in claim 6 including a limit switchoperatively responsive to said output signal to inactivate said movementimparting means in the event that the imposed limits of movement of saidshaft are exceeded.
 8. An inspection device adapted to be selectivelypositioned along three orthogonal axes relative to a workpiece forverifying the dimensions thereof, comprising: an elongated hollowhousing; a stylus shaft having a first convex terminus, the apex ofwhich has a generally conical shape, extending into one end of saidhollow housing and having a second exposed terminus for contacting saidworkpiece; a spherical bearing fixedly secured to said shaftintermediate the ends thereof whereby said shaft is supported formovement in 3* of angular freedom; a stationary bearing seat fixed withrespect to said housing and having a complementary spherical surfaceengaging that portion of said spherical bearing which is adjacent saidsecond terminus; a movable bearing seat slidably mounted within saidhousing and having a complementary spherical surface engaging thatportion of said spherical bearing which is adjacent said first terminusof said shaft thereby permitting both said movable bearing seat and saidstylus shaft to be rectilinearly translated along the major axis of saidhousing in a direction to and away from said stationary bearing seat; arectilinearly displaceable translation element slidably mounted withinsaid housing and having a concave cam surface biased directly againstsaid first conical shape terminus of said shaft, said cam surface havinga generally complementary concave contour with respect to said conicalshape terminus, whereby angular movement in 2* of freedom andrectilinear movement in 1* of freedom of said shaft will rectilinearlydisplace said translation element along the major axis of said housing;means connected to said shaft for mechanically inhibiting movementthereof in said 2* of angular freedom whenever said shaft isrectilinearly translated along said major axis in a direction away fromsaid stationary bearing seat; and transducer means operatively connectedto said translation element and responsive to displacement thereof togenerate an output sigNal.
 9. An inspection device as defined in claim 8including: a spring retainer within said housing and secured theretobetween said movable bearing seat and said translation element; and ahelical spring having a first end engaging said spring retainer andhaving a second end urged into engagement with said movable bearingseat.
 10. An inspection device adapted to be selectively positionedalong three orthogonal axes relative to a workpiece for verifying thedimensions thereof, comprising: an elongated hollow housing; a stylusshaft having a first terminus extending into one end of said hollowhousing and having a second exposed terminus for contacting saidworkpiece; bearing means located on said shaft intermediate the endsthereof by means of which said shaft may be supported for movement in 3*of angular freedom; a stationary bearing seat fixed with respect to saidhousing and engaging that portion of said bearing means which isadjacent said second terminus; a movable bearing seat slidably mountedwithin said housing and engaging that portion of said bearing meanswhich is adjacent said first terminus of said shaft thereby permittingboth said movable bearing seat and said stylus shaft to be rectilinearlytranslated along the major axis of said housing in a direction to andaway from said stationary bearing seat; a translation element slidablymounted within said housing and having a cam surface biased against saidfirst terminus of said shaft whereby angular movement in 2* of freedomand rectilinear movement in 1* of freedom of said shaft will displacesaid translation element along the major axis of said housing; a lockoutring encircling said shaft and secured thereto at a locationintermediate said second exposed terminus and said bearing meanssufficient to allow clearance between said ring and said housing upondisplacement of said shaft about the axis of said bearing means, saidring having an exterior diameter sufficiently smaller than the interiordiameter of said housing to permit said lockout ring to enter theinterior of said housing in response to displacement along the majoraxis of said shaft; and transducer means operatively connected to saidtranslation element and responsive to displacement thereof to generatean output signal.
 11. The inspective device defined in claim 8 whereinsaid transducer means comprises a valve operatively responsive todisplacement of said translation element to produce a pneumatic outputsignal.
 12. An inspection device as defined in claim 8 wherein saidtransducer means comprises an electrical pickup operatively responsiveto displacement of said translation element to produce an electricaloutput signal.
 13. An inspection device as defined in claim 8 includingspring means within said housing for urging said movable bearing seatinto engagement with said spherical bearing means.
 14. An inspectiondevice as defined in claim 8 including a helical spring normallypartially compressed into engagement with said translation element so asto urge said translation element into direct engagement with said firstterminus of said shaft.
 15. A numerically controlled machine having acollet and in combination with an inspection device as defined in claim8 comprising: a table for supporting the workpiece to be inspected;means for imparting relative movement between the table and the collet,the inspection device being mounted in the machine collet with theexposed terminus of the stylus shaft being engageable with the workpieceon the table; a programmed inspection tape means being coupled with themovement imparting means for controlling the relative movement betweenthe table and the workpiece along a predetermined path; and a recordercoupled to the transducer means for indicating dimensions of theworkpiece upon engagement of the workpiece and the inspection device.